Messages in this thread | | | Date | Wed, 27 Jul 2022 20:16:39 +0530 | Subject | Re: [PATCH] dma: ti: k3-udma: Reset UDMA_CHAN_RT byte counters to prevent overflow | From | Vaishnav Achath <> |
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Hi Peter, Vinod,
On 09/07/22 11:50, Péter Ujfalusi wrote: > > > On 7/4/22 14:13, Vaishnav Achath wrote: >> UDMA_CHAN_RT_*BCNT_REG stores the real-time channel bytecount statistics. >> These registers are 32-bit hardware counters and the driver uses these >> counters to monitor the operational progress status for a channel, when >> transferring more than 4GB of data it was observed that these counters >> overflow and completion calculation of a operation gets affected and the >> transfer hangs indefinitely. >> >> This commit adds changes to decrease the byte count for every complete >> transaction so that these registers never overflow and the proper byte >> count statistics is maintained for ongoing transaction by the RT counters. >> >> Earlier uc->bcnt used to maintain a count of the completed bytes at driver >> side, since the RT counters maintain the statistics of current transaction >> now, the maintenance of uc->bcnt is not necessary. > > Thanks for the patch, > >> Signed-off-by: Vaishnav Achath <vaishnav.a@ti.com> >> --- >> drivers/dma/ti/k3-udma.c | 27 +++++++++++++++++++-------- >> 1 file changed, 19 insertions(+), 8 deletions(-) >> >> diff --git a/drivers/dma/ti/k3-udma.c b/drivers/dma/ti/k3-udma.c >> index 2f0d2c68c93c..0f91a3e47c19 100644 >> --- a/drivers/dma/ti/k3-udma.c >> +++ b/drivers/dma/ti/k3-udma.c >> @@ -300,8 +300,6 @@ struct udma_chan { >> >> struct udma_tx_drain tx_drain; >> >> - u32 bcnt; /* number of bytes completed since the start of the channel */ >> - >> /* Channel configuration parameters */ >> struct udma_chan_config config; >> >> @@ -757,6 +755,22 @@ static void udma_reset_rings(struct udma_chan *uc) >> } >> } >> >> +static void udma_decrement_byte_counters(struct udma_chan *uc, u32 val) >> +{ >> + if (uc->tchan) { >> + udma_tchanrt_write(uc, UDMA_CHAN_RT_BCNT_REG, val); >> + udma_tchanrt_write(uc, UDMA_CHAN_RT_SBCNT_REG, val); >> + if (!uc->bchan) >> + udma_tchanrt_write(uc, UDMA_CHAN_RT_PEER_BCNT_REG, val); >> + } >> + >> + if (uc->rchan) { >> + udma_rchanrt_write(uc, UDMA_CHAN_RT_BCNT_REG, val); >> + udma_rchanrt_write(uc, UDMA_CHAN_RT_SBCNT_REG, val); >> + udma_rchanrt_write(uc, UDMA_CHAN_RT_PEER_BCNT_REG, val); >> + } > > In case of MEM_TO_MEM (or the not implemented DEV_TO_DEV) we use the > tchan's counter for position tracking, but we have the pair anyways (UDMA). > if ((uc->desc->dir == DMA_DEV_TO_MEM) > rchan bcnt reset > else > tchan bcnt reset > >> +} >> + >> static void udma_reset_counters(struct udma_chan *uc) >> { >> u32 val; >> @@ -790,8 +804,6 @@ static void udma_reset_counters(struct udma_chan *uc) >> val = udma_rchanrt_read(uc, UDMA_CHAN_RT_PEER_BCNT_REG); >> udma_rchanrt_write(uc, UDMA_CHAN_RT_PEER_BCNT_REG, val); >> } >> - >> - uc->bcnt = 0; >> } >> >> static int udma_reset_chan(struct udma_chan *uc, bool hard) >> @@ -1115,8 +1127,8 @@ static void udma_check_tx_completion(struct work_struct *work) >> if (uc->desc) { >> struct udma_desc *d = uc->desc; >> >> - uc->bcnt += d->residue; >> udma_start(uc); >> + udma_decrement_byte_counters(uc, d->residue); > > Why not before udma_start()? Thank you for your review and feedback, I have updated the addressed items in V2, Sorry for the delay in responding. V2: https://patchwork.kernel.org/project/linux-dmaengine/patch/20220727140837.25877-1-vaishnav.a@ti.com/ > >> vchan_cookie_complete(&d->vd); >> break; >> } >> @@ -1168,8 +1180,8 @@ static irqreturn_t udma_ring_irq_handler(int irq, void *data) >> vchan_cyclic_callback(&d->vd); >> } else { >> if (udma_is_desc_really_done(uc, d)) { >> - uc->bcnt += d->residue; >> udma_start(uc); >> + udma_decrement_byte_counters(uc, d->residue); >> vchan_cookie_complete(&d->vd); >> } else { >> schedule_delayed_work(&uc->tx_drain.work, >> @@ -1204,7 +1216,7 @@ static irqreturn_t udma_udma_irq_handler(int irq, void *data) >> vchan_cyclic_callback(&d->vd); >> } else { >> /* TODO: figure out the real amount of data */ >> - uc->bcnt += d->residue; >> + udma_decrement_byte_counters(uc, d->residue); >> udma_start(uc); >> vchan_cookie_complete(&d->vd); >> } >> @@ -3809,7 +3821,6 @@ static enum dma_status udma_tx_status(struct dma_chan *chan, >> bcnt = udma_tchanrt_read(uc, UDMA_CHAN_RT_BCNT_REG); >> } >> >> - bcnt -= uc->bcnt; >> if (bcnt && !(bcnt % uc->desc->residue)) >> residue = 0; >> else >
-- Thanks and Regards, Vaishnav
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